The prior art discloses devices of this type: for example, U.S. Pat. No. 3,603,387 (SCHOEFFLER) describes a device for cutting a pipe, which may be controlled at a certain distance and presenting a casing surrounding the pipe, a saw blade rotating and advancing in the casing, provided with an abrasive disc which flattens the section of the conduit, on the upstream side, to ensure tightness thanks to members of the jack type which urge the blade upstream against the thrust of the fluid circulating in the conduit to apply the blade against the upstream section of said pipe and ensure tightness. This device presents the major drawback of obliging the blade to withstand the fluid pressure whilst it rests only punctually on the jacks, which work under full load, with the result that failure of any one of the jacks may bring about rupture of the assembly.
The devices according to the invention find in particular their applications in the case of oil wells on fire. In the prior art, in this latter case, use is firstly made of devices for extinguishing by blowing, particularly by explosion, to extinguish the fire, then one generally intervenes by lateral drillings to deviate the flux towards another new zone presenting all the equipment necessary for mastering the flow.
In the general case of pipes, one generally intervenes upstream of the zone where the incident occurs, at the place where the first valve or other device for stopping the flow is located, but this does not prevent the flow of all the fluid located between the zone where the incident occurs and the zone where closure may be ensured.
In any case, it is important to be able to stop as rapidly as possible the flow of fluid at the place closest possible to the zone where the incident occurred, insofar, of course, as the exterior conditions of temperature and of pressure allow the necessary operators to approach. As will be seen hereinafter, it is obviously possible to provide placing of the devices of the invention prior to the incident, which is. possible in those cases where it is desired to modify an installation, for example, for introducing a derivation or complementary branch on a pipe.
It is also possible to envisage automatic placing with the aid of remotely controlled or numerically controlled or like robots, effecting the same operations as the operators, as will be described hereinbelow.